High conductivity materials are key components in a variety of important systems such as high power microwave systems (HPM systems) used for communications and radar. HPM systems can enable efficient and powerful microwave telecommunications or they can rapidly disrupt or damage enemy surveillance and communications hardware at significant standoff distances.
Practical HPM systems, however, are dependent on the realization of devices which are difficult to make. Two of the major technical barriers to realizing practical devices are the lack of high-current electron emitter cathodes and the RF breakdown of component materials. The intense high frequency RF electric and magnetic fields present in HPM devices cause mechanical and electrical breakdown on surfaces and/or in volumes of the HPM device. In fact, such breakdown phenomena are believed to underlie a “pulse shortening” problem that has plagued HPM sources for decades. See R. J. Barker and E. Schamiloglu, “High-Power Microwave Sources and Technologies”, chapter 10 (IEEE Press, New York, 2001).
In a number of applications, HPM device walls are required to repeatedly emit electrons from the wall surface. Repeated pulsed heating of the wall surface accompanies this repeated emission, and the repeated heating can cause surface fatigue and significant structural damage that can destroy the surfaces. The thermal shock caused by rapid temperature excursions between room temperature and the pulse heated temperature can induce defects and cracks in the wall material (typically copper) with a resultant deterioration of performance. It is therefore desirable to increase the strength of the conductor materials used for HPM wall components so that the material resists thermal shock.
Studies of strengthened copper materials for possible resistance to thermal fatigue and cracking in intense RF fields include investigation of Cu-based composites containing Al2O3 dispersoid particles. See Paper # THD20, “The Use of Dispersion-Strengthened Copper in Accelerator Designs”, by R. Valdiviez, et al., International Linac Conference (LINAC 2000), Monterey, Calif., 2000. However, the use of insulating particles such as Al2O3 results in abrupt discontinuities in electrical conductivity that can produce local hot spots. Moreover, the particles can reduce thermal conductivity. Additionally, insulating particles that reach the surface of the copper will provide localized sites of enhanced electric field.
Therefore, there is a need for a high-strength and fatigue-resistant material which is also highly electrically conductive and preferably contains no electrically insulating particles.